Helmet designs utilizing fluid-filled containers

ABSTRACT

Disclosed herein is a helmet structure for reducing kinetic energy transmission. The helmet has a first layer configured as an outside layer that serves as first contact with a source of kinetic energy and a second layer having a substance that changes state to transfer kinetic energy laterally with respect to the skull. The substance has a threshold shear yield point wherein upon contact with kinetic energy, if the threshold shear yield point of the second layer is met, the layer will at least partially liquefy to yield a liquid and flow to internal or external chambers. In one embodiment, the helmet structure is reset after contact with kinetic energy. The substance in the helmet changes state such that the substance returns to its original state prior to contact with kinetic energy and the substance returns to its original location within the helmet structure.

PRIORITY

This application claims priority to U.S. Provisional Patent Application No. 61/442,469, filed 14 Feb. 2011, the contents of which are herein incorporated by reference in their entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to safety helmet design and more specifically to reducing kinetic energy transmission after various types of impacts utilizing fluid-filled containers.

2. Introduction

In the United States, hundreds of thousands of people each year are involved in athletic, cycling or motorcycle accidents resulting in head injury. Much of the subsequent damage is caused by the transmission of kinetic energy to the brain, as well as shear forces. Although existing bicycle helmets reduce deaths and brain injuries, current designs focus more on aesthetics and aerodynamic performance than safety, in part due to market demands. In addition, the helmet industry is essentially self-regulating and therefore not likely to make significant improvements to helmets unless the improvements prove to be cost-effective and/or markedly more effective. Advances in polymeric materials provide novel approaches to helmet design and construction. Significant improvements in viscoelastic (active) dampening, low loss elastomers, and gradient rigidity materials have already given rise to enhanced athletic equipment and protective gear.

Crashes and impacts to the head in sports often result in head trauma due to the rigid construction of helmets. The severe consequences of concussive brain injuries have become increasingly recognized in many sports, particularly recently in professional football and ice hockey. It has also long been recognized that boxers often suffer significant cognitive decline, even in non-professional contests where protective head gear is required. Professional and college sports teams would likely switch to a new type of helmet, if such a design were clearly shown to reduce post-traumatic brain injury.

In addition to athletics, improved helmet designs have applications in the military. Brain injury is the leading cause of disability for military personnel deployed in Iraq and Afghanistan. Although military helmet designs have improved in recent years, they are intended primarily to prevent missile/shrapnel penetration, and do little to reduce the energy transmitted to the brain, which is a major contributor to subsequent disability. The mechanisms of traumatic brain injury due to blast forces remain unclear, but brain injuries related to explosives are by far the most common cause of death and disability in Iraq and Afghanistan. Experimental evidence indicates that the use of advanced body armor may contribute to the increase in brain injuries, both by protecting against death from injury to major non-brain organs such as the lung, and possibly by transmitting kinetic energy through larger blood vessels to the brain.

Existing helmet designs do not adequately address the critical problem: kinetic energy from the impact is transmitted to the brain through primary, secondary and tertiary mechanisms—resulting in concussion, brain damage and even death.

SUMMARY

Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or can be learned by practice of the herein disclosed principles. The features and advantages of the disclosure can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the disclosure will become more fully apparent from the following description and appended claims, or can be learned by the practice of the principles set forth herein.

Disclosed is a structure for improved safety helmet designs utilizing fluid-filled containers that reduce the kinetic energy induced by impact and rotational forces. The safety helmet will better protect the brain by limiting both direct missile trauma and secondary kinetic effects. The safety helmet has a first layer that comes in direct contact with an object and a second layer having a substance that changes state. Optionally, the helmet can have a third or more layers having a substance that changes state. The second layer and optional additional layers each have a threshold shear yield point wherein upon contact with kinetic energy, if the threshold shear yield point of a layer is met, the layer will at least partially liquefy to yield a liquid and flow into pockets of space. Subsequent threshold shear yield points in a layer can differ from previous threshold shear yield points and become progressively higher in shear yield force required to cause liquid to flow. The liquid is ejected through an orifice and flows to internal holding chambers or space external to the helmet. In one embodiment, the helmet can be reset such that after an impact causing liquid to flow, the substance state of the liquid is changed such that the liquid is returned to its original state prior to contact with kinetic energy. In another embodiment, subsequent layers can contain both foam and liquid dispersion elements. The foam can be composed of any suitable compressible material formulated to have a range of mechanical compression strength.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and other advantages and features of the disclosure can be obtained, a more particular description of the principles briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only exemplary embodiments of the disclosure and are not therefore to be considered to be limiting of its scope, the principles herein are described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 illustrates a side view of a safety helmet with layers having fluid-filled containers;

FIG. 2 illustrates an exemplary safety helmet method embodiment;

FIG. 3 illustrates a side view of safety helmet layers having substance-filled bubbles;

FIG. 4 illustrates a side view of safety helmet layers having substance-filled containers;

FIG. 5 illustrates a side view of safety helmet layers having substance-filled bubbles and compressible foam structures;

FIG. 6 illustrates a side view of safety helmet layers having substance-filled containers and compressible foam structures;

FIG. 7 illustrates a side view of safety helmet layers having substance-filled bubbles and internal holding chambers;

FIG. 8 illustrates a side view of safety helmet layers having substance-filled containers and internal holding chambers;

FIG. 9 illustrates a side view of safety helmet layers having substance-filled bubbles and an external orifice;

FIG. 10 illustrates a side view of safety helmet layers having substance-filled containers and an expandable sac; and

FIG. 11 illustrates an exemplary safety helmet reset method embodiment.

DETAILED DESCRIPTION

Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure.

The present disclosure addresses the need in the art for improved safety helmet designs. A safety helmet design is disclosed that reduces both the kinetic energy induced by impact and rotational forces. A brief introductory description of safety helmets is provided followed by a discussion of mathematical modeling used to optimize helmet layer design. A more detailed description of improved safety helmet designs utilizing fluid-filled containers will then follow. While a helmet is used in the example embodiment, the layering principles can also be applied to a wall, body armor, a vehicle, or any protective layer that could use the principles disclosed herein. Accordingly, various embodiments of the disclosure include a wall having a series of layers and disclosed herein, body armor having the series of layers as well as a vehicle having an outer covering including the series of layers disclosed herein. The disclosure proceeds to discuss primarily a helmet embodiment.

Traditional design for both military and recreational helmets includes a rigid outer material to prevent penetration of the skull and brain, as well as some type of lining material to absorb some of the shock and to enhance comfort. However, few modern designs adequately address the critical problems leading to brain damage: kinetic energy transmitted to the brain and rotation (particularly axial acceleration/deceleration).

By using novel materials and composites that are organized upon mathematically defined principles to maximize the relative dissipation of transmitted kinetic energy, as well as to limit rotational components, development of a new design for helmets and body armor should markedly reduce posttraumatic brain injuries from various types of insults and impacts. The initial target outcome is a set of disruptive technological advances in helmet design that improve the survivability of impact trauma to the head for use in military and civilian applications.

Stacks of various materials can be used in experiments to determine the abilities of the various materials to dissipate and spread out external forces. Mathematical modeling can be used to extrapolate from experimental data to the behaviors of actual helmets constructed of the various material stacks by constructing local models and constructing local-to-global models.

A local model refers to a mathematical model of a single cylindrical stack. Such a model allows calculation, based upon an exogenous force exerted on the top surface of the stack, the amount of force transmitted to a particular point either internal to the stack or on the surfaces of the stack.

Consider a particular stack on which is imposed a rectangular coordinate system (x, y, z). Further, suppose that the vector function F(x, y, z) represents the magnitude of the force experienced at point (x, y, z) of the stack from a known exogenous impact on the stack. Yet further, suppose that experimental data results in measurement of the value of F(x, y, z) at N particular stack points, say

(x _(i) ,y _(i) ,z _(i))(i=1, . . . ,N)

Based on the geometric description of the stack, the properties of the materials composing the stack, and an analysis of the physics of force transmission through the stack, the general mathematical form of the function F(x, y, z), up to a set of parameters. For example, in a simple case, the function might have the form:

F(x,y,z)=ax+by+cz

a linear function, involving three parameters a, b, c, which must be determined. Generally, the experimental data results in an over-determination of a, b, c, so that no set of values for a, b, c exactly matches the experimental data. The best that can be done is to determine the values of a, b, cis some “optimal fashion”—that is, so that some error function is minimized. The most common such error function is the sum of squares function:

${E\left( {a,b,c} \right)} = {\sum\limits_{i = 1}^{N}\left( {{F\left( {x_{i},y_{i},z_{i}} \right)} - {ax}_{i} - {by}_{i} - {cz}_{i}} \right)^{2}}$

In case F(x, y, z) is linear, as in the above example, the determination of a, b, c is just the well-known problem of linear regression analysis. However, in actual practice, the function F may involve more or fewer parameters and is generally highly non-linear, especially for materials with complicated behaviors. In such instances, the error function E is a much more complex function and the problem of minimizing the sums of the squares of the errors is a non-linear optimization problem, which we have had considerable experience addressing.

In order to proceed from the local models to actual helmets configurations, an accepted technique from finite-element analysis can be used, namely subdividing a helmet configuration into a large number of elemental configurations, the analysis of each of which can be handled by a local model, and then analyzing the interaction among adjacent elemental configurations.

For the case of the helmet configurations, the surface of the helmet can be divided into a triangular lattice. Corresponding to each triangle, a triangular prism can be obtained by a radial cut into the helmet along each side of the triangle. Each triangular prism can be regarded as embedded within a circular stack and thus subject to the analysis of a local model, which would allow an assessment of the transmission of forces between adjacent prisms in response to an exogenous force anywhere on the helmet surface.

Of particular interest would be the proportion of the initial energy which is transmitted to the bottom of the prisms, the maximum forces transmitted, and their respective locations. This information can be used to compare the effectiveness of various material stacks and helmet configurations.

Having disclosed some mathematical modeling used to optimize helmet layer design, the disclosure now turns to FIG. 1 and FIG. 2. FIG. 1 and FIG. 2 illustrate an improved safety helmet design that reduces both the kinetic energy induced by impact and rotational forces. The safety helmet will better protect the brain by limiting both direct missile trauma and secondary kinetic effects. The safety helmet 102 receives contact of an object that transfers kinetic energy to a first layer 104, 202. The first layer can be a composite composed of a discrete reinforcement and a continuous binder, such as a polymer, or can be any other material such as Kevlar or steel that can spread kinetic energy A polymer is a large molecule composed of repeating structural units, the units typically connected by covalent chemical bonds. Polymers are both natural and synthetic materials with varying properties. Natural polymeric materials include shellac, and cellulose and synthetic polymers include neoprene, PVC, silicone and more. The discrete reinforcement is composed of particles that can have differing sizes, shapes and can be different materials such as ceramic or glass. The reinforcement is at least one particle and has particles with a size greater than one micron. The continuous binder binds particles to one another to yield the composite in the first composite layer of the safety helmet.

The helmet uses a second layer having a substance that changes state to transfer kinetic energy laterally with respect to the skull 204. Optionally, the helmet can have a third or more layers having a substance that changes state. The third layer is adjacent to the second layer, the fourth layer is adjacent to the third, and so on. The second layer 106 and optional additional layers each have a threshold shear yield point wherein upon contact with kinetic energy, if the threshold shear yield point of a layer is met, the layer will at least partially liquefy to yield a liquid and flow into pockets of space. A threshold shear yield point is the point at which a substance changes state. Different Bingham liquid plastics or other liquids having similar properties can be used in the helmet. Bingham plastic liquids are characterized as having no flow, or solid behavior, when the applied shear force is below a threshold value. Above this threshold, the liquid will have a shear thinning behavior, or a thick liquid flow.

Subsequent threshold shear yield points in a layer can differ from previous threshold shear yield points and become progressively higher in shear yield force required to cause liquid to flow. For example, a third layer can have one or more threshold shear yield points higher than a second layer, and a fourth layer can have one or more threshold shear yields point higher than a third layer. Upon impact with a source of kinetic energy, layers can partially or completely liquefy to reduce the impact that a head receives. Alternately, subsequent threshold shear yield points in a layer can be the same or lower as previous threshold shear yield points.

FIG. 3 and FIG. 4 illustrate side views of safety helmet layers. The first layer is an outside layer 302, 402 that comes into contact with an object. The second layer 304, 404 adjacent to a respective first layer 302, 402 can consist of bubbles 306 or other containers 406 filled with a substance, such that when a threshold shear yield point for the layer is met, liquid flows from the bubbles 306 or other containers 406 to displace force laterally with respect to the skull. Liquid can be ejected through an orifice and flow to internal space such as internal storage chambers 108, 408 or can flow to space external to the helmet 110. The internal storage chambers 108 can be initially collapsed 110 and can expand as the liquid flows into the chambers 112 or chambers can be rigid. Helmet layers can be bonded by at least one storage chamber. Layers of phase changing liquid plastics can be separated by storage layers that can serve as expandable binding layers. Boundaries between layers can be thick, thin, rigid, flexible, interconnected, not interconnected or any combination thereof. The substance-filled containers can be made from any impermeable plastic, for example polypropylene. The liquids can be made from suitable liquids with a suitable range of formulation. Examples include silicone oils, polyvinyl alcohol mixtures with cross-linking, polyethylene oxides or other synthetic polymers, and mixtures with diluents including water and silicone oils.

In one embodiment, second and additional layers in a structure can contain both foam and liquid dispersion elements. The foam can be composed of any suitable compressible material, for example polyurethane, formulated to have a range of mechanical compressible strength. A second layer can compress and have expansion structures such that at least one expansion structure expands into an expansion zone in the second layer to transfer kinetic energy upon impact. Each expansion structure has a first base configured to be adjacent to the first layer and a first tip, and a second base configured to be adjacent to a third layer and a second tip, such that the first tip is in contact with the second tip in a mirrored configuration. For example, a helmet can have a first composite layer that receives contact of an object that transfers kinetic energy and a second layer having a substance that changes state to transfer kinetic energy laterally with respect to the skull and can have expansion structures that expand into an expansion zone in the second layer. The second layer can have multiple foam structures with graded physical properties. The graded physical properties can be created from the chemical composition of the foam, by incorporation of different sizes of reinforcements, or by physical shaping of the foam. Subsequent layers can contain any number of foam dispersion elements in any location within the layers. Each subsequent layer can contain differing sizes of reinforcements, physical shaping, etc. from at least one other of the layers.

FIG. 5 and FIG. 6 illustrate structures having a second layer with both liquid and foam dispersion elements. A first layer 502, 602 is an outside layer that comes into contact with an object. A second layer 504, 604 has both liquid and foam dispersion elements. A second layer 504 can contain graded foam structures 506 and liquid-filled bubbles 508. When the threshold shear yield point for the second layer is met, the bubbles pop causing liquid to flow into empty internal space 510 surrounding the bubbles and the foam compresses and expands into empty space 510 to absorb shock from an impact. A second layer 604 can contain graded foam structures 606 having elements with differing shapes and liquid-filled containers 608. When the threshold shear yield point for a second layer is met, liquid-filled containers can open, causing liquid to flow into empty space 610 surrounding the containers and foam can compress and expand into empty space 610 to absorb shock. Alternately, liquid can flow from containers 612 into an expandable sac that expands when liquid flows 614.

FIG. 7 illustrates fluid from popped bubbles flowing into internal holding chambers and FIG. 8 illustrates fluid from containers flowing into internal holding chambers. A first layer 702, 802 is an outside layer that comes into contact with an object. A second layer can have liquid dispersion elements. A second layer 704 can contain liquid-filled bubbles 706 that can pop when the threshold shear yield point for the layer is met. Liquid can flow into empty space surrounding the bubbles 708 and can flow into an internal storage chamber 710. A second layer 804 can contain liquid-filled containers 806 that can open for liquid to flow into an internal storage chamber 808 when the threshold shear yield point for the layer is met.

FIG. 9 illustrates fluid from popped bubbles flowing into an external orifice and FIG. 10 illustrates fluid from opened containers flowing into an external orifice. A first layer 902, 1002 is an outside layer that comes into contact with an object. A second layer 904, 1004 has liquid dispersion elements. A second layer 904 contains liquid-filled bubbles 906 that can pop when the threshold shear yield point for the layer is met. The liquid can flow into an orifice 908 to external space by flowing through a first layer 902 or by any other means. Additionally, liquid can flow into internal storage chambers 910 when the threshold shear yield point for a layer is met. A second layer 1004 can contain liquid-filled containers 1006 that can open when the threshold shear yield point for the layer is met and can have graded foam structures 1008 that compress upon impact with an object. Liquid can flow to space external to a helmet using an orifice 1010 an can flow through a first layer 1002 or by any other means. Liquid can flow into an expandable sac 1012 that is external to the second layer and/or helmet structure. Alternately, liquid can flow into an expandable sac internal to the helmet 1014 or liquid can flow to expandable sacs both internal 1014 and external 1012 to the helmet. The expandable sac 1012 can expand when liquid flows into the sac and can serve as a visual indicator to a helmet wearer or to others the severity of an impact. Any combination of fluid-filled bubbles, fluid-filled containers, fluid dispersion techniques and compressible foam for slowing or redirecting the transfer of force away from the head from an impacting object are contemplated.

In one embodiment, the helmet can be reset such that after an impact causing liquid to flow, liquid flows from a container or other source back to its initial location or a new location within the helmet. FIG. 11 illustrates resetting a helmet structure after impact. After an impact, another device can be used or the helmet itself can reset such that liquid returns to its original state prior to contact with an object that transfers kinetic energy 1102 and returns the liquid to its original location within the structure 1104. Alternately, after an impact the liquid returns to its original state prior to contact with kinetic energy and the liquid returns to another location within the structure. For example, after an impact a helmet with an external expandable fluid-filled sac is reset such that the fluid flows from the sac back into one or more containers through an orifice or other means. Alternately, after an impact a helmet with an external expandable fluid-filled sac is reset such that fluid flows from the sac back into one or more empty containers although the fluid was originally stored in bubbles. This more complex helmet is designed to handle multiple impacts appropriate for football helmets, motorcycle helmets and military helmets.

The various embodiments described above are provided by way of illustration only and should not be construed to limit the scope of the disclosure. Thus, for a claim that recites a structure that deflects and spreads kinetic energy, the structure could apply in any application disclosed herein (vehicle, helmet, body armor, building protection, etc.) as well as other structures not listed. Those skilled in the art will readily recognize various modifications and changes that may be made to the principles described herein without following the example embodiments and applications illustrated and described herein, and without departing from the spirit and scope of the disclosure. 

1. A structure for reducing kinetic energy transmission, the structure comprising: a first layer configured as an outside layer that serves as first contact with a source of kinetic energy; a second layer comprising a substance adjacent to the first composite layer, the second layer changing state having a threshold shear yield point, wherein upon interaction with the source, if the threshold shear yield point of the second layer is met, the second layer will at least partially liquefy to yield a liquid; and space for the liquid in the second layer to flow.
 2. The structure of claim 1, wherein a second layer is adjacent to a third layer comprising a substance, the third layer changing state having a threshold shear yield point, wherein upon interaction with the source, if the threshold shear yield point of the third layer is met, the third layer will at least partially liquefy to yield a liquid.
 3. The structure of claim 2, wherein the threshold shear yield point of the second layer differs from the threshold shear yield point of the third layer.
 4. The structure of claim 2, wherein the threshold shear yield point for the third layer is higher than the threshold shear yield point for the second layer.
 5. The structure of claim 1, wherein, if the threshold shear yield point is met, the liquid will be ejected through an orifice to space internal to the structure.
 6. The structure of claim 1, wherein, if the threshold shear yield point is met, the liquid will be ejected through an orifice to space external to the structure.
 7. The structure of claim 4, wherein space internal to the structure is an internal storage chamber.
 8. The structure of claim 6, wherein the internal storage chamber is initially collapsed.
 9. The structure of claim 6, wherein the internal storage chamber expands as liquid flows into the chamber.
 10. The structure of claim 1, wherein layers are bonded via at least one internal storage chamber.
 11. The structure of claim 2, wherein the boundary between the second layer and the third layer is at least one of thick, thin, rigid, flexible, interconnected and not interconnected.
 12. The structure of claim 1, wherein the structure is reset after contact with a source kinetic energy, the steps comprising: changing the substance state of the liquid such that the liquid is returned to its original state prior to contact with kinetic energy; and returning the liquid to its original location within the structure.
 13. The structure of claim 12, wherein the liquid is returned to a different location within the structure. 